[PATCH 5/5] Add fair "control groups" scheduler

Srivatsa Vaddagiri
2007-09-24T16:45:43Z

Enable "cgroup" (formerly containers) based fair group scheduling.
This will let administrator create arbitrary groups of tasks (using
"cgroup" psuedo filesystem) and control their cpu bandwidth usage.

Signed-off-by : Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by : Dhaval Giani <dhaval@linux.vnet.ibm.com>

---
include/linux/cgroup_subsys.h | 6 ++
init/Kconfig | 24 +++++---
kernel/sched.c | 122 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 145 insertions(+), 7 deletions(-)

Index: current/include/linux/cgroup_subsys.h
===================================================================
--- current.orig/include/linux/cgroup_subsys.h
+++ current/include/linux/cgroup_subsys.h
@@ -36,3 +36,9 @@ SUBSYS(mem_cgroup)
#endif

/* */
+
+#ifdef CONFIG_FAIR_CGROUP_SCHED
+SUBSYS(cpu_cgroup)
+#endif
+
+/* */
Index: current/init/Kconfig
===================================================================
--- current.orig/init/Kconfig
+++ current/init/Kconfig
@@ -327,13 +327,6 @@ config FAIR_GROUP_SCHED
This feature lets cpu scheduler recognize task groups and control cpu
bandwidth allocation to such task groups.

-config RESOURCE_COUNTERS
- bool "Resource counters"
- help
- This option enables controller independent resource accounting
- infrastructure that works with cgroups
- depends on CGROUPS
-
choice
depends on FAIR_GROUP_SCHED
prompt "Basis for grouping tasks"
@@ -345,8 +338,25 @@ choice
This option will choose userid as the basis for grouping
tasks, thus providing equal cpu bandwidth to each user.

+ config FAIR_CGROUP_SCHED
+ bool "Control groups"
+ depends on CGROUPS
+ help
+ This option allows you to create arbitrary task groups
+ using the "cgroup" psuedo filesystem and control
+ the cpu bandwidth allocated to each such task group.
+ Refer to Documentation/cgroups.txt for more information
+ on "cgroup" psuedo filesystem.
+
endchoice

+config RESOURCE_COUNTERS
+ bool "Resource counters"
+ help
+ This option enables controller independent resource accounting
+ infrastructure that works with cgroups
+ depends on CGROUPS
+
config SYSFS_DEPRECATED
bool "Create deprecated sysfs files"
default y
Index: current/kernel/sched.c
===================================================================
--- current.orig/kernel/sched.c
+++ current/kernel/sched.c
@@ -179,10 +179,16 @@ EXPORT_SYMBOL_GPL(cpu_clock);

#ifdef CONFIG_FAIR_GROUP_SCHED

+#include <linux/cgroup.h>
+
struct cfs_rq;

/* task group related information */
struct task_grp {
+#ifdef CONFIG_FAIR_CGROUP_SCHED
+ struct cgroup_subsys_state css;
+#endif
+
/* schedulable entities of this group on each cpu */
struct sched_entity **se;
/* runqueue "owned" by this group on each cpu */
@@ -221,6 +227,9 @@ static inline struct task_grp *task_grp(

#ifdef CONFIG_FAIR_USER_SCHED
tg = p->user->tg;
+#elif CONFIG_FAIR_CGROUP_SCHED
+ tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
+ struct task_grp, css);
#else
tg = &init_task_grp;
#endif
@@ -6950,3 +6959,116 @@ int sched_group_set_shares(struct task_g
}

#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+#ifdef CONFIG_FAIR_CGROUP_SCHED
+
+/* return corresponding task_grp object of a cgroup */
+static inline struct task_grp *cgroup_tg(struct cgroup *cont)
+{
+ return container_of(cgroup_subsys_state(cont, cpu_cgroup_subsys_id),
+ struct task_grp, css);
+}
+
+static struct cgroup_subsys_state *
+cpu_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ struct task_grp *tg;
+
+ if (!cont->parent) {
+ /* This is early initialization for the top cgroup */
+ init_task_grp.css.cgroup = cont;
+ return &init_task_grp.css;
+ }
+
+ /* we support only 1-level deep hierarchical scheduler atm */
+ if (cont->parent->parent)
+ return ERR_PTR(-EINVAL);
+
+ tg = sched_create_group();
+ if (IS_ERR(tg))
+ return ERR_PTR(-ENOMEM);
+
+ /* Bind the cgroup to task_grp object we just created */
+ tg->css.cgroup = cont;
+
+ return &tg->css;
+}
+
+static void cpu_cgroup_destroy(struct cgroup_subsys *ss,
+ struct cgroup *cont)
+{
+ struct task_grp *tg = cgroup_tg(cont);
+
+ sched_destroy_group(tg);
+}
+
+static int cpu_cgroup_can_attach(struct cgroup_subsys *ss,
+ struct cgroup *cont, struct task_struct *tsk)
+{
+ /* We don't support RT-tasks being in separate groups */
+ if (tsk->sched_class != &fair_sched_class)
+ return -EINVAL;
+
+ return 0;
+}
+
+static void
+cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cont,
+ struct cgroup *old_cont, struct task_struct *tsk)
+{
+ sched_move_task(tsk);
+}
+
+static ssize_t cpu_shares_write(struct cgroup *cont, struct cftype *cftype,
+ struct file *file, const char __user *userbuf,
+ size_t nbytes, loff_t *ppos)
+{
+ unsigned long shareval;
+ struct task_grp *tg = cgroup_tg(cont);
+ char buffer[2*sizeof(unsigned long) + 1];
+ int rc;
+
+ if (nbytes > 2*sizeof(unsigned long)) /* safety check */
+ return -E2BIG;
+
+ if (copy_from_user(buffer, userbuf, nbytes))
+ return -EFAULT;
+
+ buffer[nbytes] = 0; /* nul-terminate */
+ shareval = simple_strtoul(buffer, NULL, 10);
+
+ rc = sched_group_set_shares(tg, shareval);
+
+ return (rc < 0 ? rc : nbytes);
+}
+
+static u64 cpu_shares_read_uint(struct cgroup *cont, struct cftype *cft)
+{
+ struct task_grp *tg = cgroup_tg(cont);
+
+ return (u64) tg->shares;
+}
+
+static struct cftype cpu_shares = {
+ .name = "shares",
+ .read_uint = cpu_shares_read_uint,
+ .write = cpu_shares_write,
+};
+
+static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ return cgroup_add_file(cont, ss, &cpu_shares);
+}
+
+struct cgroup_subsys cpu_cgroup_subsys = {
+ .name = "cpu",
+ .create = cpu_cgroup_create,
+ .destroy = cpu_cgroup_destroy,
+ .can_attach = cpu_cgroup_can_attach,
+ .attach = cpu_cgroup_attach,
+ .populate = cpu_cgroup_populate,
+ .subsys_id = cpu_cgroup_subsys_id,
+ .early_init = 1,
+};
+
+#endif /* CONFIG_FAIR_CGROUP_SCHED */

--
Regards,
vatsa